I have an H-pipe system on my Van. I love it. The sound from the pipes became more mellow, and distinct. I noticed a slightly better toque response, and a better idle.
I put my crossover directly under and just ahead of my universal on the transmission. I also put my mufflers and cats directly below the manifold outlet, and ran the pipes back from there. I was able to use a smaller body muffler, with larger inlet and outlets.
It is a simple set up and I like the results I got.